LA TOUSSUIRE, France >> An angry Chris Froome accused Vincenzo Nibali of “unsportsmanlike” behavior after the defending Tour de France champion accelerated away when the race leader stopped with a stuck wheel on the toughest Alpine climb on Friday.

Nibali, who went on to win Stage 19, said Froome tore into him verbally at the finish.

“He was very angry but that’s his problem,” the 2014 Tour winner said.

Froome said a stone or piece of asphalt jammed between his brake and rear wheel on the Col de la Croix de Fer climb, forcing him to pull up momentarily to unjam it. While Froome stopped, Nibali rode away.

Stopping short of saying Nibali should have waited for him, Froome said: “It was almost as if my mechanical (problem) provoked his attack.”

At the finish, Froome added, “I told him exactly what I thought of him.”

Nibali’s win on the exhausting Alpine stage rescued what has otherwise been a disappointing Tour for the Italian.

There were also fireworks in the race and another spectator incident appearing to involve Froome.

On the stage’s final climb to the La Toussuire ski station, Nairo Quintana launched his most sustained and telling attack against Froome, and this time got the better of the 2013 champion.

Showing for the first time at this Tour that he’s not untouchable, Froome chose not to stay with the Colombian, his closest rival, as he accelerated away and started eating into the British rider’s overall race.

Froome said he preferred to save energy for Saturday’s last Alpine stage, which features two very hard climbs. So he rode steadily, limiting the damage, rather than hunt down Quintana, he said.

Froome’s lead of 2 minutes, 38 seconds over Quintana, down from 3:10 at the start, should be enough to get the British rider through the last competitive day in the Alps before the final stage to Paris on Sunday, which is largely ceremonial and won’t change the overall podium standings.

Still, the smaller cushion will force Froome to watch Quintana very carefully on Saturday’s two very tough climbs and means he cannot afford a bad day.

Nibali wasn’t Froome’s only problem on Friday.

TV images of the final climb appeared to show a spectator stepping into the road and spitting toward the race leader as he sped past. Froome, who said urine had been thrown at him in Stage 14, called the latest incident “appalling behavior.”

As for Nibali, he said he didn’t see that Froome had pulled up on the Croix de Fer ascent, even though television images appeared to show him looking back over his left shoulder at the Team Sky rider before accelerating away from him.

Nibali said he was speaking to a teammate, not looking back at Froome, and that he always had planned to attack on that climb.

Nibali also said he was “very disappointed” at the way Froome spoke to him at the finish and that, as far as he was concerned, no rule says other riders must wait when a race leader has an accident.

On the final climb to La Toussuire, the Italian overtook French rider Pierre Rolland. Sweat pouring off his legs, he rode solo to the finish, with the cross from the chain around his neck in his mouth at the end.

Riding with the No. 1 bib as the defending champion, Nibali has had a tough Tour, unable to match Froome. He started the day in seventh place, 8:04 behind. But with the time clawed back on his winning ride, Nibali jumped to fourth place, now 6:44 behind Froome.